Tracy James knew the drug she'd just swallowed was working when her old injuries from high school started twitching with new life. Pressure throbbed from a forgotten busted knee. Her ankle tingled. The fingers she'd sprained roller-skating decades back began to ache. Whatever the 37-year-old had just taken, it shot feeling back into the long-gone ailments.

"When I did vomit, it was one of the most amazing moments of my life."

For the past 45 minutes, the hut had been dark and silent, the air dripping with jungle moisture. James and nearly 20 others were sitting cross-legged on ornate rugs. One by one, a pair of Shipibo shamans peered into the face of each visitor, ceremonial chants slipping from their lips.

It was June 2009. James, a pretty, curly-haired Jamaican-American woman, was then calling Los Angeles home. As a life coach, she was interested in rewiring the mind-body split. A friend had suggested she make the trip to the Peruvian jungle, where the indigenous tribes had a powerful liquid that could radically shake up one's consciousness. Now, James was miles into the bush surrounding the town of Iquitos. Her first dose of the nasty, rust-colored liquid was blasting through her system.

Emily Utne

Dennis McKenna has taken ayahuasca hundreds of times since 1981.

Courtesy of Dennis McKenna

For ayahuasca ceremonies, users typically gather in a hut at night, when visions are more intense.

Shutterstock / Dr. Morley Read

Expert Dennis McKenna has spent time with the Peruvian tribes who harvest the vine.

Shutterstock / Jason Mintzer

A ceremonial hut in Peru.

Waves of nausea began crashing over James. Strange geometric shapes filled her vision. Around her, some people sobbed. Others threw up into buckets. James left the wooden hut topped with a thatched roof for the outhouse. The diarrhea hit so frequently, she just sat outside in a chair, feeling weak and terrible. Oh my gosh, she cringed, waiting for the next bout.

Two Shipibo women — tiny people with sun-cured faces wearing the tribe's traditional sky-blue shirts — approached. As one chanted, the other woman placed her mouth against the alarmed James' stomach. The shaman began sucking out the bad energy, a practice known as chupa. After 20 minutes, James was amazed to feel great. She walked back into the hut, was hit with another wall of nausea, and puked.

"When I did vomit, it was one of the most amazing moments of my life," she says today. "After all that purging, I just had this amazing feeling of peace."

The psychoactive brew goes by many names. William S. Burroughs and Allen Ginsberg called it yagé. In Brazil, it's known as hoasca. Other aliases include the Spirit Vine, the Vine of the Soul, and the Vine of the Dead.

Its most common name is ayahuasca. The indigenous cultures of the Amazon have brewed the plant concoction, with its naturally occurring dose of the hallucinogen DMT (N,N-Dimethyltryptamine), for centuries. It is generally prepared in a brew made from the vine of a species called Banisteriopsis caapi.

In recent years, the West has caught on. The tea cropped up in the Jennifer Aniston flick Wanderlust and the Showtime series Weeds; proponents include everyone from Sting to The Howard Stern Show's Robin Quivers. This, despite the fact that it's mostly illegal here. Possessing the plants is OK, but concoctions made from it are banned, except in religious ceremonies, because DMT is a Schedule I drug. Still, one ayahuasca expert estimates that on any given night, 50 to 100 ayahuasca groups are in session in New York City alone, and a new, burgeoning business in the States is organizing drug excursions to Peru, where the substance is legal.

Some of the same doctors and researchers who have, in recent years, gotten FDA approval for breakthrough studies involving MDMA and psilocybin mushrooms are now turning their attention to ayahuasca. Preliminary work suggests the brew could help treat depression, chronic addiction, and fears of mortality. People with less-defined diagnoses but a hunger for something missing say ayahuasca offers something ineffable: compassion, connectedness, spirituality.

"Ayahuasca is penetrating American society, and its highly successful people, way more than any other psychedelic," says Rick Doblin, head of MAPS, the Multidisciplinary Association for Psychedelic Studies, a nonprofit research association based in Santa Cruz, California. "The number of people who have had incredible experiences with ayahuasca, if they could all surface in the public sphere at the same time, it would be absolutely astonishing."

In a greenhouse at the University of Minnesota, Dennis McKenna walks past the cacao (chocolate) and the Punica (pomegranate) and strides straight to the back corner, where the vines of the plant Banisteriopsis have twisted around each other — and nearby electrical cords — to reach the room's rafters.

McKenna, a white-bearded professor wearing wire glasses and a denim shirt tucked into his jeans, points at one of the younger vines, a supple green stem the width of a pencil.

"This is nothing," he says, explaining that mature plants can reach 1,500 feet and weigh several tons. "Usually, the part you use is the thickness of a finger."

McKenna would know: He has drunk ayahuasca several hundred times since 1981. An ethnobotanist and ethnopharmacologist by trade, McKenna first tangled with psychedelics as a teen coming of age in the '60s. He tried everything from LSD to jimsonweed but never ayahuasca: There was none.

"It was this rare, legendary thing," McKenna remembers.

The first record of ayahuasca arrived in the West in 1908, thanks to British botanist Richard Spruce, who mostly described lots of vomiting. Harvard ethnobotanist Richard Evan Schultes followed up a half-century later with the first academic account. Around the same time, Beat author William Burroughs wrote letters depicting his quest for the tea to Allen Ginsberg, collected in 1963 as The Yage Letters. But in Western literature, there wasn't much more than that.

Seeking to change that, McKenna embarked on his first trip to South America at age 20. A decade later, he returned, this time to research his dissertation. After months in the jungle, he brought plant samples back to his lab, where he showed for the first time how ayahuasca works.

To make the brew, shamans boil together two Amazonian plants for many hours, sometimes days. As they simmer, the DMT contained in one of the plants mixes with the other one, the Banisteriopsis vine, and its key ingredient: monoamine oxidase inhibitors, or MAOIs. Normally when people ingest DMT — a not-uncommon compound in nature — the monoamine oxidase in our gut knocks it out. But the Banisteriopsis allows the hallucinogen to reach the brain.

By the middle of the 20th Century, several Brazilian churches splintered off from the shamans and took ayahuasca into a formal setting. In 1991, one of these — a group called the Uniao do Vegetal, or UDV — invited Mc­Kenna to one of its twice-monthly ceremonies during which the tea is administered as a sacrament. (A New Mexico-based branch of the church won a 2006 U.S. Supreme Court case allowing it to use ayahuasca in its ceremonies. The church has about 300 members in six U.S. states, including a group in Florida.)

In a room with 500 other people, Mc­Kenna drank first one cup, then a second, and was plunged into one of the most vivid ayahuasca visions of his life: a molecule's-eye view of photosynthesis or, as he explains it, "the force on which life depends."

When McKenna returned to his body, he writes in his new book, The Brotherhood of the Screaming Abyss, "I knew that I had been given an inestimable gift."

McKenna began devising a study to look at the biomedical effects of ayahuasca, and within two years, he was back in Brazil. On this trip, he brought along a team that included Dr. Charles Grob, a psychiatrist who heads the Division of Child and Adolescent Psychiatry at UCLA's medical school.

"Nowadays, the word is out," Grob says. "But when we did this, I'd say, 'We're doing an ayahuasca study,' and people would say, 'Aya-what-sca?' "

For about a month in the summer of 1993, the team of the Hoasca Project ran tests on 15 randomly selected members of the church, all of them men who had been using ayahuasca regularly for at least ten years. The scientists ran the same tests on similarly aged men who had never been exposed to ayahuasca.

The researchers measured every biological metric they could think of — blood pressure, heart rate, pupil dilation, body temperature — and used structured psychiatric interviews to get where their instruments couldn't: inside the participants' minds.

Many of the men had struggled with alcoholism and depression prior to joining the church, Grob learned. They credited ayahuasca with transforming their outlook. "In some cases," Grob says, "they felt like it had saved their lives."

When the researchers left Brazil and started processing their data, the bloodwork came back with one of the project's most startling discoveries: The long-term ayahuasca users showed higher levels of the transporters of serotonin, the brain chemical that regulates mood.

"That's the target that antidepressants work on, and here it was significantly elevated in the drinkers [of ayahuasca]," McKenna says.

Deficits in serotonin transporters are also connected to problems like alcoholism and depression — the same issues the 15 subjects said the ayahuasca had helped cure.

"Here we have a medicine that apparently reverses these deficits, something no other medicine is known to do," explains McKenna. "And there's also a correlation to behavioral change. You can't say it caused it, but there's definitely a correlation."

Today, 20 years after the study, Mc­Kenna is preparing to revisit the findings. Within a year, he aims to raise enough money to fund a new study, this time in Peru, to look at the effects of ayahuasca on people with posttraumatic stress disorder.

He hopes that additional research will help him establish his ultimate goal: a destination medical clinic in Peru.

"If we can bring together the best of shamanism and the best of psychotherapy, I think we can offer a new paradigm for healing," says McKenna. "What we're really trying to do here is revolutionize psychiatry."

Lisa Yeo doesn't look like a junkie. The 47-year-old has shimmering blond hair and clear skin and wears a stylish tangerine shirt. It's Halloween, and her two dogs — a shih tzu and a dachshund — yap incessantly as trick-or-treaters come to the door of her house in Toronto.

Just eight years ago, she weighed 80 pounds and was missing her two front teeth.

Yeo's father gave her her first alcoholic drink at age 6, and she was drinking alone by age 11. As a teen, she developed a cocaine addiction, and in her early 20s, she set out on a path that would take her to heroin, crack, and prostitution.

On August 11, 2005, as cops walked her out of a hotel where they had found her shooting up, Yeo realized she was finally ready to change.

She went to rehab for a year, then a recovery house for another two years. But she still wasn't totally sober: For 18 years, she'd been receiving a court-ordered dose of the opiate substitute methadone. Now, she wanted off all drugs, once and for all.

As Yeo reduced her dose, her body started breaking down. Doctors told her that quitting the methadone was dangerous and advised her to just accept it as a fact of her life. To Yeo, the thought of staying on methadone was unbearable, and she began contemplating suicide.

Then she heard of a famous Canadian addiction specialist, Dr. Gabor Mate. Yeo set up a meeting.

"I told him this big, long story, and at the end of it, he said, 'Lisa, I think I can offer you a potential way out of this,' " Yeo remembers. "It was just like, 'Really?' "

First, Yeo spent a summer at a treatment clinic in Mexico, where she used other traditional plant medicines, iboga and ibogaine, to help wean her body off opiates. By October 2012, Yeo was ready for step two and boarded another plane to Mexico, this time for a weeklong ayahuasca retreat.

The night of her first ceremony, Yeo walked onto a round platform with a roof open to the jungle around it. Not long after she drank — "it tasted bitter, but it didn't taste as bad as some of the things I'd ingested in my life" — Yeo began to feel something prodding at her liver, damaged by hepatitis C.

"I felt what I thought of as a vine going into the area where I had the pain and circle, circle, circle," Yeo remembers. "Then there would be this release, and the pain would be gone."

The night of the second ceremony, Yeo's experience shifted: This time, she saw a slideshow of people who had shown her kindness, "babysitters to social workers to prison guards," Yeo remembers. "It was like flash cards, and at the very end was my mom."

Yeo has since done a second ayahuasca retreat with Mate and credits the vine with helping her discover who she is without substances.

"It has given me a go-to place of safety and a knowing of how to be gentle with myself when any tormenting thoughts creep in," Yeo says. "It just lifts the trauma; it lifts the pain."

Treatment for addiction disorders is one of the most promising areas of therapeutic ayahuasca use, in part because doctors still don't have many other good options.

"Someone walks in your office today, you're going to basically say the same thing your predecessor might have said 50 or 60 years ago, which is, 'Find a 12-step group, and if you're lucky and it's a good fit, maybe it will help,' " explains Grob. "Otherwise, we don't have a whole hell of a lot to offer."

The psycho-spiritual experiences that ayahuasca provides — "like a mystical-level state," Grob says — seem to offer an effect similar to that of certain faith-based aspects of 12-step groups: showing addicts that there is a power greater than themselves.

When Mate first heard of ayahuasca, he had recently published his book on addictions, In the Realm of Hungry Ghosts. People kept writing him, asking if he knew about "this weird plant," Mate remembers. Eventually, he decided to try it himself.

During his first retreat, Mate saw the connection to treating addiction right away.

"The ayahuasca experience just dissolved my defenses," he says. "I experienced a deep sense of love, tears of joy racing down my face."

Mate began organizing retreats of his own. He brought in shamans to lead the ceremonies and used his own training to help participants prepare for, process, and integrate what they experienced.

"It's not a question of 'Here's a drug that's going to fix you,' " Mate explains. "It's 'Here's a substance under the effect of which you'll be able to do a kind of self-exploration that otherwise might not be available to you or otherwise might take you years to get to.' "

In 2011, a Canadian First Nations community contacted Mate to treat some tribe members with chronic substance-dependence problems. Mate agreed and in June arrived at a remote village for the first of two retreats. A team of researchers, led by addiction specialist Dr. Gerald Thomas, came along.

Since Grob and McKenna's study in 1993, some limited research had been done on ayahuasca: Scientists had performed brain scans of ayahuasca users and administered freeze-dried ayahuasca in a lab. But no one had followed up on ayahuasca's therapeutic potential. Thomas and his team were ready to continue the work.

The group set up in the tribe's longhouse, a spacious wooden structure with a stove in the middle and straw on the floor. Twelve members were participating in the first ceremony, and that night, before they drank, Mate led them in conversation about their addictions.

"When they were talking about trauma, for many of them, that was the first time they ever shared that with anybody," Mate says. "They were entering into deep pain."

Before the retreat, Thomas and his team administered psychiatric evaluations to measure the 12 participants on factors like hope, quality of life, mindfulness, and emotional regulation. After the ceremony, researchers repeated the tests — first two weeks later, then four weeks, then once per month for half a year.

The results, which they published in June of this year in the journal Current Drug Abuse Reviews, came back promising. Alcohol, tobacco, and cocaine use decreased among the participants. On the psychological surveys, the subjects' quality-of-life scores increased, as did the ratings for mindfulness, empowerment, outlook, and hopefulness.

At the six-month mark, the team also interviewed 11 of the study participants and asked them to rate the experience on a scale from one to ten. The mean response came back at 7.95. One 30-year-old man told the researchers, "With my last experience with the ayahuasca, I really faced myself. Like, my fear, my anger. Which really, I think is a big part of my addictions... I wish I was introduced to it like 20 years ago. It could have saved me a lot of time and trouble."

Tracy James' experience with ayahuasca didn't end with that first night in the jungle. The L.A. life coach's retreat lasted another 12 days. She went through multiple ceremonies, punishing repeats of that first gut-churning episode.

However, she also had vivid visions. In one, she went on a quest for a gold ring hidden underwater. In another, a beautiful woman told her she was calling James back home. Once, James imagined she was greeted by a group of elfin-like creatures. There, she felt the comfort of home, of belonging. Still, once the retreat was over, she never wanted to take ayahuasca again.

"I had a lot of ceremonies that were really hard," she says.

But back home, similar dreams filled her head at night. That feeling of belonging, of being home — she began to see it as a signal. When the opportunity came up to study with the same Shipibo shamans, she signed on.

Today, James is based out of Fort Myers. With a business partner, she runs AyaIntegral (ayaintegral.com). Two or three times a year, the pair leads a group down to Peru for 12-day retreats with Shipibo shamans. Customers pay around $2,600 for the total ayahuasca experience. "People say it's like a year of therapy in a night, and it's no joke," she says today.

The increase in such ayahuasca tourism has morphed Iquitos, Peru, into a boomtown on the Amazon Basin. In 2012, 250,000 visitors traveled through the once-sleepy inland port — many searching for the magic drug.

Today at the Iquitos airport, travelers are as likely to be offered ayahuasca — or at least canisters of a dubious brown liquid — as a taxi. The stuff so thoroughly permeates the city that a New York Times travel dispatch from September opens, "Before we begin, a disclaimer: In Iquitos, Peru, your correspondent did not consume the shamanic hallucinogen ayahuasca."

The influx of tourists seeking transcendence has brought with it new problems. When Joshua Wickerham, a sustainability consultant, was invited to a conference on psychedelics in Oakland, California, this April, he got an earful.

"The people in the ayahuasca community were talking about all of these issues, as ayahuasca is becoming this global phenomenon," Wickerham recalls. "There were so many people from so many walks of life saying, 'There is so much good happening here, but there are also real problems.' "

An idea was born: a kind of TripAdvisor for ayahuasca centers. In early November, Wickerham launched the Ethnobotanical Stewardship Council as a nonprofit devoted to assuring the sustainability and safety of traditional plants like ayahuasca. Wickerham envisions the ESC developing, with the community's input, into a consensus certification model.

"I think the ESC can help educate the seekers," Wickerham says, "so there's some way to differentiate when there's a neophyte who lands at the Iquitos airport and asks the cabdriver, 'Where should I go for ayahuasca?' "

As far as psychedelics go, studies show that ayahuasca is on the relatively safe side. For it to be lethal, a user would have to take about 20 times more than the standard ceremonial dose. (For alcohol, that number is ten times more than a normal serving.) Brain scans of ayahuasca users indicate that the brew doesn't have a neurotoxic effect.

"The knee-jerk reaction is to say, 'Oh, it's a dangerous hallucinogen,' but look at the actual mortality rate," says Mc­Kenna. "If you look at the number of people who die from adverse reactions to aspirin, ayahuasca is considerably safer."

The main risks are psychological, proponents say. "That's where a good shaman comes in," says McKenna.

But in the Wild West that is Iquitos, it can be hard to tell which shamans are the real deal. Some serve a counterfeit brew laced with the witchcraft-associated plant known as toé. Others have impure intentions.

In the ayahuasca community, there's a collection of well-known horror stories: the German woman who returned from Peru with a report of being sexually assaulted by her "shaman." The two French citizens who died during their trip — one from a heart attack, the other from a likely interaction with his prescription medications. The worst, though — the story held up as a warning to those who seek blindly — is the story of an 18-year-old Californian named Kyle Nolan.

Nolan set out for the Shimbre Shamanic Center, a Peruvian ayahuasca lodge run by a shaman calling himself Mancoluto, in August 2011. When Nolan never showed up for his flight home, his worried parents went to Peru to find him. First, Mancoluto claimed that Nolan had taken off in the middle of the night, but his body was later found in a grave on the center's property. No one has yet been charged.

To Wickerham, stories like this illustrate why the ESC is necessary. He hopes to work with the governments of countries like Peru and Ecuador to show them that they don't have to resort to heavy-handed regulatory legislation — that the community can monitor itself.

"I hope we can prevent another tragedy."

When Dr. Brian Rush started a crowdfunding campaign for ayahuasca research, he didn't know what to expect.

The campaign for ATOP — the Ayahuasca Treatment Outcomes Project — launched on Indiegogo in August 2013. By the time it closed in October, Rush and his team had raised $34,000 from 450 people. Some of them, Rush says, had personal experiences with ayahuasca; others had been touched by addiction; still more were simply intrigued.

Most interesting of all was the support from doctors.

"I got notes from physicians and psychiatrists in the U.S. and Canada who have been using ayahuasca under the table in clinical practice and really support this work," says Rush. "I don't think I expected that."

Rush, an addiction researcher with a doctorate in public health, first heard of ayahuasca in 2011 and decided to travel to Peru to learn more. He checked into an ayahuasca center called Takiwasi and, during a ceremony, confronted his 20-year addiction to nicotine.

"I was laid flat out in a coffin, and my three children were standing around me," says Rush. "Then I started purging, and it felt like I was purging the tobacco poison."

Not long after Rush returned home, he gave up smoking for good.

"I had quit before, but this time was different," he says. "It's like I have no memory of smoking. I don't have any tactile memory in my hands. That was a year and a half ago, and I haven't had a cigarette."

Having studied addiction science for 30 years, Rush asked the Takiwasi center what data it had. The answer was: not much. When he realized that other, similar programs also lacked decent evaluation data, he decided to change that.

"I said, 'I am in your service,' " he recalls.

The Indiegogo campaign funded the project team's first planning meeting, the kickoff of a study that will be several years long. The meeting took place in Peru at the end of October and brought together 40 international researchers to help design the project.

They decided that ATOP will be an umbrella over studies in several South American countries, each looking at ayahuasca in the treatment of drug and alcohol abuse. By the end, the researchers hope to have definite answers on whether addicts treated with ayahuasca see a verifiable reduction in alcohol- and drug-related harms.

"It's real clear that all we have now is kind of anecdotal evidence and small studies with short-term follow-up," says Rush. "This is a potential approach that a lot of people have some confidence in, and at least enough confidence to say, 'We need more studies. We need to know more.' "